Process of dehydrating sodium hydrosulfite.



.UNITED STATESPATENT OFFICE.

ALBRECHT SCHMIDT, OF H6CHS I-ON-THE-\IAIN;# MANY, ASSIGNOR TO FARBWERKEVORM. MEISTER LUGIUS & BRUNIN G, OF HGUhSLON-THE-MAIN, GERMANY, ACORPORA- TI ON OF GERMANY.

PROCESS OF DEHYDRA'IING SODIUM HYDROSULFITE.

Specification of Letters Patent.

Patented June 30, 1908.

Application filed June 12, 1906. Serial No. 321,345.

Dehydrating Sodium Hydrosulfite Contain-- ing Water of Crystallization,of which the following is a specification.

It is known that sodium hydrosulfite crystallizes from concentratedaqueous solutions with 2 molecules of-water of crystallization. I havefound that if such or stallized sodium hydrosulfite Na,S,O,.2H ob-,

t-ained, for instance, by hard pressing the crystalline magma whichseparates from the cold concentrated aqueous.solution to be heated to6070 (1, preferably while stirring, the large transparent crystalsbecome opaque; water is set free and the mass be comes a granular magma,totally changing its aspect. A dehydrating process occurs here analogousor similar to that which occurs on heating crystallized sodium carbonatein its water of crystallization. By the present .process a granularsodium bydrosul'lite is separated. From this granular mass, which mayeven. be allowed to cool [or a short time without becoming hydratedagain, the sodium hydrosullite may be separated by pressing or draining,whereupon the salt may be dried in a vacuum, or else the magma,containing the dehydrated hydrosulfite may be quickly dried directly ina vacuum. The crystallizedsodium hydrosulfitemay also be transformed bysimply heating it, if there be present Indifferent, non-dehydratlngliquids, 1nsolublo mwater, whichpernut more readily a n equalization ofthe temperature between the wall of the vessel and the crystalline mama, such, for instance, as Xylene, toluene, enzene or the like. Forinstance, the solid 11 draulically pressed hydrated crystals may eintroduced iecc by piece into a carted vessel provider with an agitatorand containing some toluene, the temperature of the massbcing l\'( )lbetween 50 and 65 C, or a little above; t to transfornmtion occurscontinuously. 'lhc magmadhus obtained is then further worked up as abovedescribed. I

Having now described my invention, What I claim is:-

I. The. herein described process of dehydrating sodium hydrosultitccontainin water of crystallization, which consists in lieat ing thecrystals to a temperature at which they split up to .l'orm a granularsolid and a liquid, separating said granular solid from as much aspossible of said liquid by pressing, and then completely drying saidsolid in a vacuum.

2. The herein described process of d-chydrating sodium hydi osultitecontaining water of crystallization, which consists in heating thecrystals to a temperature at which 1 they split up to form a granularsolid and a liquid, separating the liquid from the solid mass, and thenin drying pasty mass in a vacuum.

In testimony, that I claim the foregoing as my invention, I have signedmyv name mpresence of two subscribing witnesses.

' ALBRECHT SCHMIDT. Witnesses:

JEAN GRUND, (tun. (hwun

